1. Field of the Invention
This invention lies in the field of inert gas generators. More particularly, it concerns an inert gas generator which utilizes the products of combustion from a furnace or other source, along with a supply of fuel and combustion air, to generate inert blanketing gas with a selected minimum value of oxygen content.
2. Description of the Prior Art
Removal of flammable liquids from tanks, vessel holds, and the like, where the vapor-pressure of the liquid is less than atmospheric pressure, is typically accomplished by pump-out of the liquid from its containment. In such cases, as the liquid is withdrawn, a volume of gas at least equal to the volume of the withdrawn liquid must flow into the containment space to avoid less-than-atmospheric pressure within the containment volume.
If the entering gas is air, and in view of the flammable nature of the liquid, an explosive mixture of air and flammable vapor from the liquid is formed, and a great hazard exists. This hazard is particularly significant in marine transport of flammable liquids, particularly because the discharge of oils is accomplished "in-port". Also, because the oils discharged are flammable, regulations require that gases admitted to containing spaces for the oils be "inert". That is, their oxygen content is limited to 4%, where dry air contains approximately 21% oxygen. At 4% O.sub.2, there is not sufficient oxygen to create an explosive condition within the containment space, such as it may be.
On shipboard, it would be possible to make use of Inert Gas Generators for supply of inert "blanketing gases", but such gases, produced by carefully-controlled combustion, demand large quantities of fuel which is an expensive, as well as an energy-wasteful practice. Simultaneously, it is required that there be certain fuel firing in the ship's boilers. However, because, with limited boiler firing, it is virtually impossible to prevent the presence of 8%-10% O.sub.2 in the stack flue gases, it has not been possible to make use of the boiler stack flue gases for "blanketing", such as discussed, as a supplement to blanketing gases as produced by inert-gas generation at another point aboardship. Such use of boiler flue gases is, potentially, a big step toward fuels conservation in the provision of a required quantity of inert blanketing gases in avoidance of explosions as the cargo is moved to land-based containment.